Swift is full of syntactic sugar. One particular taste of sweet is the callAsFunction feature. If a type has a method of that name, you can call an instance or value of that type like a function. That’s used in SwiftUI to pass actions around in the environment, for example. Quick demo: See how the call looks like there’s a function updateWidgets(newerThan:) but actually it’s calling the value itself?
Primitive Obsession is not called “Primitive Preference” for a reason: we can find ourselves clinging to primitives like addicts, even when every aspect of our project nudges us, hints, and screams that we should be doing something different. It’s never just “a string”. It’s never just “an integer”.
I often forget the name of this thing, then I search for it, and forget it again later. It’s the Whole Value Pattern. The “Whole Value” pattern means you should get rid of using primitive or literal data types as quickly as possible. (Since Swift has no non-object primitives, you have to look a bit harder to spot these, but “literal value” is a pretty good indicator.)
I’m back from my vacation and very deep into programmin already. Before I left, my subconscious mind brought up the notion of a Lens (functional programming) while I was modelling tabular data in Swift and I think this is a very cool approach to keep value types clean and easy to test. I use lenses in my current project to provide a specialized interface to operate with the table. The lenses provide access to column and row iterators, independent of the table’s underlying data structure. This way the table doesn’t have to worry about all this stuff.